Shock layer radiation is a form of aerodynamic heating that becomes significant at some entry velocities, depending on the vehicle trajectory and the planet’s atmosphere. Radiation heating is commonly computed with an appropriate method known as the tangent slab approximate in which the radiative heat flux is simplified to be a one-dimensional equation and, thus, the effects of radiation intensities from other directions are neglected.

In this work, a three-dimensional radiation ray-tracing algorithm was developed and demonstrated for several planetary entry applications, including the next-generation hypersonic aerodynamic inflatable decelerators. It is shown that the three-dimensional radiation ray-tracing corrects the overprediction of the tangent slab approximation on radiative heating by as much as 15% at the stagnation point, and as much as 200% in separated regions.

The algorithm was implemented using Fortran 90 in a code called the PArallel Radiation Ray Tracing (PARRT), a general, parallel, multi-block, structured-grid 3D radiation ray-tracing code that corrects the radiative surface heat fluxes that are commonly calculated with the tangent slab approximation method for hypersonic planetary entry vehicles.

PARRT can accept axisymmetric and/or 3D codes, and can also provide frequency-dependent radiation intensity along the radiation rays. It is a simple and fast post-processing code.

This work was done by Alireza Mazaheri and Christopher Johnston of Langley Research Center, and Siavash Sefidbakht of Ohio State University. NASA is seeking partners to further develop this technology through joint cooperative research and development. For more information about this technology and to explore opportunities, please contact This email address is being protected from spambots. You need JavaScript enabled to view it.. LAR-18238-1

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This article first appeared in the December, 2017 issue of Tech Briefs Magazine.

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